1. Department of Anaesthesia; Assistance Publique Hôpitaux de Paris; Hôpital Raymond Poincaré; Garches France
2. INSERM; Boulogne Billancourt France; France
3. Orthopedic Surgery; Assistance Publique Hôpitaux de Paris; Hôpital Raymond Poincaré; Garches France
4. Department of Outcomes Research; Cleveland Clinic; Cleveland Ohio USA
5. Department of Anaesthesia; Hôpital Bicêtre; Bicêtre France